1. Field of the Invention
The present invention relates to a noise suppression system, a sound acquisition apparatus, a sound output apparatus, and a computer-readable medium storing a program causing a computer to function as the sound acquisition apparatus or the sound output apparatus.
2. Description of the Related Art
Networking for electronic equipment used in households etc. is advancing to the point where not only information equipment such as personal computers but also household electrical goods such as audio equipment (for example, digital music players) and visual equipment (for example, televisions and image recording/reproducing equipment) are being connected to IP-based networks such as LAN (Local Area Network).
Further, mobile communication terminals such as mobile phones that are fitted with a wireless LAN function (so-called dual mode terminals) also exist that are capable of connecting to IP networks such as LAN.
Various electronic equipments can then be connected to an IP network so as to enable cooperative operation between equipment or remote operation by a user. The types of equipment that are becoming networked are tending to increase. In addition to image recording units such as video cameras and digital still cameras, it is also predicted that typical household equipment such as refrigerators and washing machines will become networked.
The bulk of such electronic equipment handles sound. This means that noise relating to sound can be problematic. For example, when talking on a mobile phone while watching television broadcasting, there is the possibility that the called party will be able to hear the sound of the television. Recognition precision is also reduced in the case of speech recognition using a personal computer etc. when music is played back by audio equipment as a result of the impinging of replayed sound.
Sound noise also can occur as a result of so-called “acoustic echo”. When audio is outputted from a speaker while sound is acquired by a microphone at equipment including both a speaker and a microphone, the sound outputted by the speaker becomes wrapped around and is picked-up by the microphone. The audio outputted by the speaker containing the audio picked-up by the microphone is referred to as an “acoustic echo” and is the cause of deterioration in the quality of sound acquired by the microphone and howling.
Technology referred to as “echo canceling” is widely employed to suppress acoustic echoes in telephone terminals etc. “Echo canceling” refers to sound output from a speaker that is taken as a reference signal. Acoustic echo estimated based on this reference signal is then suppressed in the sound acquired by the microphone.
This “echo canceling” is disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2003-124849 etc. This echo canceller reads in inputted sound (speaker output sound) outputted by the speaker as a reference signal, generates a pseudo echo, and subtracts this pseudo echo from the audio inputted from the microphone in order to suppress acoustic echo.
This echo canceller is pre-recorded with audio data for specific noise such as the sound of vehicle windscreen wipers. When a specific noise is then detected, the pre-recorded audio data is referred to and specific sounds are suppressed in the acquired sound.